This invention relates to liquid level sensors and, in particular, to a liquid level sensor capable of sensing predetermined water levels and may be adjusted to a zero level.
The prior art abounds with liquid or water level sensing apparatuses, typically used to perform a function upon the occurrance of the water, such as for example, rain sensing mechanisms as disclosed in the U.S. patents to Keeler, No. 1,153,314 issued Sept. 14, 1915; Hirschman, No. 1,135,798 issued Apr. 13, 1917; and the patent to Conway, No. 1,174,827 issued Mar. 7, 1916. All of the above utilize a porous paper fuse link, which is destroyed upon the absorbtion of water, thereby releasing a spring loaded contact which completes a function e.g. closes a window, activates an alarm, etc. A much later patent to Crockett, Sr., U.S. Pat. No. 4,001,531 issued Jan. 4, 1977 discloses a water-soluble disc element that is disposed proximate a surface. Upon the appearance of water at a given level on the surface, the water soluble disc is caused to dissolve, permitting a spring activated plunger to close the contacts of a switch affixed thereon.
The need for a liquid or water level sensor becomes apparent when one considers the fact that many homes today are provided with basements that are either completed to function as a recreation or study area or are used for storage. In either condition, it is desirous that they be kept dry. Also, frequently, the hot water heater, humidifier or sump pump is located in the basement and an indication of a malfunction as soon as it occurs is most desirable so that protective measures may be undertaken before substantial damage is sustained. Thus, a small, inexpensive portable liquid level sensor is a desirable and necessary item.
The present invention overcomes the shortcomings found in the prior art by providing a liquid level sensor that may be adjusted to a zero level, by being placed in intimate contact with a surface upon which the water is to be sensed, and also may be adjusted to a desired preset water level for other applications.